Here are the five keys that will make it happen.
1. Favre magic
Favre is 21-5 all-time against the Bears, including 12-1 on the road. If Favre can pull off the upset, it will mark the Packers' 12th straight road win in the series, which would match the league record held by San Francisco (against the Rams, from 1987 to 1998) and the Rams (against San Francisco, amazingly, from 1969 to 1980).
Favre could fill a career highlight package against the Bears alone. His career high for completions is 36, against the Bears in 1993. His career high for passing yards is 402, also against the Bears in 1993. His career high for touchdown passes is five, against the Bears in 1995. His two longest touchdown passes — 99 yards to Robert Brooks in the other 1995 game and 85 yards to Donald Driver in the 2002 game at the University of Illinois — came against the Bears. And who can forget his longest touchdown run, a 36-yarder through the Halloween slop in 1994?
Favre must find some of that magic for the Packers to stage the upset. In the Bears' seven-game winning streak, they haven't surpassed 20 points in any of the last six games. If Favre can hit a couple of haymakers, that might be all the points the Packers will need.
2. Take care of the ball
Turnovers have been the Achilles' heel for the Packers all season — their minus-11 ratio is tied for next-to-last in the NFL — and a bellwether for the Bears.
Favre's 19 interceptions lead the league, and he's on pace to shatter his career high. The Bears have intercepted 16 passes, a figure that is tied for third most in the league.
With points expected to be hard to come by — the Las Vegas over-under on the game is set at 31 points — the Packers can't afford to give away possessions or set the Bears up in prime scoring position.
3. Be patient
Unless the Bears manage to score a couple of quick touchdowns, Favre and the rest of the Packers' offense must understand that patience will be a virtue. As long as the game is close and the score is low, there is no sin in punting again and again.
These Bears, as has been well-documented, are statistically superior to the dominating 1985 Super Bowl defense, which is frequently hailed as the best ever. During their winning streak, they've allowed 3, 6, 13, 17, 9, 3 and 10 points.
If the game is close, the type of wild throws Favre made against Philadelphia could be deadly. The Packers must concentrate on picking up first downs, winning the field-position battle, and hope Donald Driver or Donald Lee can turn a catch into a big play.
4. Run the ball
The Bears rank third in the league in yards allowed per rush. The Packers rank 31st in yards gained per rush. By those standards, running the football seems like a recipe for disaster.
The Packers, however, can't afford to give up on the run. The Bears are second in the league in sacks with 35. They do it with overwhelming play from their front four — especially defensive ends Adewale Ogunleye and Alex Brown — not exotic blitzing schemes. The constant pressure is a big reason why the Bears have intercepted so many passes and lead the league in third-down defense.
If the Packers want to keep Favre upright and healthy, they must keep the Bears off balance and stay out of third-and-long situations.
5. Put the ball in Orton's hands
It's no secret that rookie quarterbacks more often than not are liabilities, not strengths. This is the case in Chicago, which is led by Kyle Orton.
Orton's record is tremendous, mostly because he's avoided deadly mistakes. Still, he's completed only 54.5 percent of his passes, with nine touchdowns and 12 interceptions.
The Packers must take away Chicago's running attack, which is easier said than done. The Packers' run defense has faded as the season has progressed. The Bears went into the season with the one-two punch of Thomas Jones and rookie first-round pick Cedric Benson. Benson is out with a knee injury, but Jones is nearing 1,000 yards and Adrian Peterson has filled Benson's role and is averaging 6.0 yards per carry.
Lawrence is a regular contributor to PackerReport.com. Send comments to firstname.lastname@example.org